Technical Field
The present invention relates to an optical deflector including a mirror, a method for mirror finishing of a mirror by cutting, and a Light Detection and Ranging (LiDAR) device including the optical deflector.
Description of the Related Art
A conventional Light Detection and Ranging (LiDAR) device determines the distance to an object by irradiating the object with light emitted from a light source, and receiving the light reflected back from the object on a light receiver via a mirror unit. The LiDAR device determines the distance to the object based on the time of flight of the light that is emitted from the light source, reflected back from the object, and received by the light receiver (the time lag between the light emission and the light reception), and speed of light in an optical-pulse time-of-flight method.
A conventional optical deflector for a LiDAR device includes a reflector (such as a mirror) secured to a separate rotatable member. The reflector is generally a so-called glass reflector made of a glass member coated with a layer of metal deposition.
When securing a glass reflector in an optical deflector, it is difficult to firmly secure the reflector to a rotatable member with a great securing force while keeping the flatness of the mirror surface. These two objects are generally in the relationship of trade-off. If the reflector is firmly secured to the rotatable member to ensure good securing, the mirror surface will be deformed. If the reflector is not firmly secured to the rotatable member to keep the flatness of the mirror surface, the reflector may be loosened by the vibration and impact given from the outside. In the latter case, such a structure cannot ensure the reliability of the LiDAR device including the optical deflector against the vibration and impact from the outside when the LiDAR device is used as a vehicle component. In either case, the structure for mounting a glass reflector on a rotatable member has one of the disadvantages.